STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Net sales	$ 38,029	$ 34,834
Cost of sales	24,454	21,692
Gross profit	13,575	13,142
Operating (income) expenses:
Selling expenses	590	577
General and administrative expenses	4,076	3,189
Gain on disposal of equipment		(5)
Research and development costs	4,384	2,315
Total operating expenses	9,050	6,076
Operating income	4,525	7,066
Other income (expense):
Interest and dividend income	126	95
Other income		952
Gain on sale of investments	1,327	25
Interest expense	(352)	(236)
Total other income	1,101	836
Income before income taxes	5,626	7,902
Income tax expense	1,176	1,790
Net income	4,450	6,112
Other comprehensive loss, net of tax:
Unrealized gain (loss) from marketable equity investments, net of income taxes	1,371	(1,037)
Comprehensive income	$ 5,821	$ 5,075
Basic & Diluted income per share:
Basic net income per share	$ 1.17	$ 1.56
Diluted net income per share	$ 1.13	$ 1.5
Weighted-average common shares outstanding:
Basic	3,796,516	3,910,940
Diluted	3,936,194	4,078,087